Laguna Negra, Catamarca

Laguna Negra is a lake in the Catamarca Province of Argentina. It lies on the Puna high plateau next to two other lakes and salt flats. The lake is less than 2 metres (6 ft 7 in) deep and forms a rough rectangle with a surface of 8.6 square kilometres (3.3 sq mi). Laguna Negra loses its water through evaporation, and is replenished through surface runoff and groundwater which ultimately originate to a large part from snowmelt. The waters of the lake are salty.

On the southeastern shore of the lake, microbialites grow in the shallow water. These are structures formed by carbonate and microorganisms including diatoms and various bacteria. These structures have a layered internal structure and colours ranging from green to orange-pink to black. They have been compared to Precambrian stromatoliths, which were among the oldest forms of life on Earth.